I have improved the fabrication and operation of pressure-regulating spool valves. Previous suggestions for such spool valves include U.S. Pat. Nos. 3,174,505; 4,071,042; 4,119,294; and 4,478,250; and the subject matter of a U.S. patent application entitled PRESSURE REGULATING SPOOL VALVE AND METHOD, naming Raymond E. Johnson as inventor and owned by the assignee of this application.
My invention improves over previous suggestions for pressure regulating spool valves in several respects. Thes include making the valve compact, inexpensive to manufacture, easily adjustable to meet performance standards, fast and reliable in operation, responsive to control, and less subject to hysteresis error.